This is a request for a Mentored Patient-Oriented Research Career Development Award (K23). The training and research components of this proposal provide the applicant with the skills and research settings necessary to test the internal (construct) validity and external (concurrent and predictive) validity of the vascular depression construct. The applicant's career goal is to become an expert in the nosology of late-life neuropsychiatric disorders. The 4-year training plan focuses primarily on the development of expertise in the statistical methods used to carry out thorough psychometric evaluations of diagnostic entities in order to arrive at valid diagnostic criteria. Since diagnostic criteria for late-life disorders may encompass more than phenomenology, secondary training goals are to develop expertise in identifying MRI hyper-intensities and in neuropsychological contributions to the differential diagnosis of depression and dementia. The 4-year research plan complements the training plan by proposing a series of sequential studies that operationalize and test specific diagnostic criteria for vascular depression. The research plan has the following aims: 1. to test the internal (construct) validity of the nosological entity, vascular depression, and determine the diagnostic criteria that most accurately identify its occurrence by applying latent class cluster analysis to three existing late-life depression datasets;2. To test the external validity of the vascular depression construct by classifying patients from two completed late-life depression treatment trials as vascular depressed or not (non-vascular) according to criteria established in Aim 1, and then comparing the groups with respect to concurrent (phenomenology at baseline) and predictive (short-term treatment response) validity;3. To test prospectively the external validity of the nosological construct in an 8-week open treatment trial of escitalopram and to determine whether African Americans have a higher than expected rate of vascular depression. In summary, this proposal is the first to attempt a systematic psychometric evaluation of the internal and external validity of the proposed diagnostic category, vascular depression. The strategies applied in this proposal move beyond the use of expert consensus that has dominated previous DSM classification efforts and the diagnostic criteria validated here will likely include MRI and neuropsychological test scores. Thus, vascular depression may serve as a prototype for future diagnostic classifications both in terms of methodology and content;that is, the criteria for vascular depression will likely rely on a combination of phenomenology and laboratory tests in addition to requiring evidence of internal and external validity. This application addresses a major public health concern, the identification and treatment of depression in older adults, the fastest growing segment of the population. It specifically focuses on African American older adults, who have especially high rates of hypertension and may be particularly prone to vascular depression.